Conventionally, the production of magnet wheels for alternators with claws uses forging operations.
Rotors which are equipped with permanent interpolar magnets require the production of grooves for accommodation of the magnets, and of magnet lips in the teeth of the magnet wheels. The magnet lips ensure the retention in place of the permanent magnets, which are subjected to the effects of the centrifugal force when the rotor is rotating.
It is known to produce the grooves of magnet receptacles and the magnet lips by means of a machining operation which takes place after the forged magnet wheel has been obtained. In the industrial process of production of the magnet wheels, this machining operation has the disadvantage of increasing the duration of production and the cost of the part.
U.S. Pat. No. 7,676,902 B2 describes a method for production of a magnet wheel in which the operation of machining of the grooves for accommodation of the magnet is eliminated. The magnet wheel is obtained by using only forging operations. The grooves for accommodation of the magnet and the magnet lips are preformed by hot forging. Cold forming tools are then used to complete the production of the grooves and lips, as well as of the chamfers provided in the teeth of the magnet wheel. These cold forming tools are actuated radially, i.e. according to the radius of the magnet wheel.
It is desirable to provide other solutions for the forging of the grooves for accommodation of the magnet and of the magnet lips, in order to be able to comply with the various constraints which apply in the industrial processes for production of magnet wheels.